1. Field of Invention
The present invention relates to ventilation of a hospital patient through an endotracheal tube inserted into the trachea of a patient. More particularly, the present invention relates to a flow system that provides for continuous removal of secretions from within an intubated patient.
2. Prior Art
Intubation involves the insertion of a conduit into the trachea of a patient. One of the most commonly used conduits is an endotracheal tube. For intubation, the distal end of the endotracheal tube is extended into the trachea of a patient. The endotracheal tube generally terminates in a patient at a position above the carina and interior to a position between the second and fourth thoracic vertebrae. Gasses may then be introduced into the lungs of the patient through the endotracheal tube.
Purposes for intubation include providing mechanical ventilation of a patient's lungs (e.g., when a disease prevents the patient from normal breathing-induced ventilation), and providing a conduit for anesthetic gasses during a surgical procedure. To prevent the escape of gasses past the endotracheal tube once inside of an intubated patient, an inflatable cuff may be included at the distal end of the endotracheal tube. When inflated, the cuff seals the annular passageway between the endotracheal tube and the tracheal wall. This inflatable cuff may be formed integral with and surrounding the endotracheal tube. There are approximately 17,000 patients in critical care units in the United States on any given day, of which approximately 60% may require intubation. Although intubation is often a life-saving maneuver, intubation unfortunately tends to create serious adverse effects on a patient's ability to clear secretions and particles from their lungs.
In a non-intubated person, inhaled particulate matter is normally cleared from the lungs by a patient's natural mucociliary transport system. The natural mucociliary transport system is composed of cells, which line the tracheobronchial tree and which have cilia (tiny hairs) on their surfaces. The cilia sweep particles up so that coughing can expel the particles from the body. These cells also produce mucous that provide a fluid phase to facilitate transport. Secretions from the tracheobronchial tree are also normally removed through the constant motion of the tiny cilia which line the trachea.
In an intubated patient, however, the endotracheal tube tends to impair the functioning of the natural mucociliary transport system. Initiation of a cough requires glottic closure in order to generate the intrathoracic pressure required to effectively expel material from the trachea. The presence of the endotracheal tube prevents an intubated patients from closing their glottis. Further, ciliary function and mucociliary transport in the trachea, which may be impaired by infection such as pneumonia or tracheobronchitis, is also impaired by the endotracheal tube, which tends to block the upward movement of secretions. Thus, it is common for intubated patients to have internal secretions pool in the patient's lungs distal to the sealing cuff on an endotracheal tube.
Accumulation of fluids, particulate matter, and internal secretions in the lungs of intubated patients give rise to critical problems and infections in these patients, such as atelectasis and pneumonia. The risk of such infection and other problems generally increase with increased length of time of intubation. It is well-documented that a relatively high mortality rate is associated with prolonged intubation. Removal of pooled secretions from intubated patients is, therefore, an integral part of the care of such patients.
The standard technique for removing internal secretions from an intubated patient is to suction pooled secretions directly from the lungs of the patient. This standard technique, however, has significant disadvantages. For example, direct suctioning requires the periodic efforts of a trained health care professional and often occurs on an intermittent basis of about once every one to two hours, due to labor and time constraints. Secretions within the lungs of an intubated patient, therefore, may accumulate and pool for significant time periods. Further, every time the ventilator system is exposed to allow direct suctioning of pooled secretions from an intubated patient, the risk for contamination and subsequent infection tends to increase. Direct suctioning has been associated with severe complications including hypoxemia, cardiac arrhythmias, decreased oxygen delivery, cardiac arrest, mucosal trauma, and raised intracranial pressure.
The standard technique for removing secretions from an intubated patient is, therefore, inherently inefficient and risks contamination of the patient. The goal of the present invention is to provide an apparatus and technique for directing air flow within an endotracheal tube and for removing secretions from an intubated patient, while overcoming problems associated with prior devices and techniques.